Answer: They were alarmed to see communism gaining a foothold in the Western Hemisphere.
The interests that America had in Cuba mostly came from their fears of communism during the Cold War. After WWII, the United States and the Soviet Union saw the world as a competition between communism and capitalism. The United States, therefore, was alarmed to see that Cuba wanted to establish a communist government. Americans saw this as a sign of danger, as it would mean that communism was gaining a foothold in the Western Hemisphere.
